title: Effect of verapamil on pulmonary reflexes in the vascularly isolated canine lung: physiology.
abstract: Breathing frequency (BF) may be affected by changes in the percent inspired CO2 administered to vascularly isolated lungs. Pulmonary CO2 probably affects BF, in part, through a secondary effect of CO2 on airway smooth muscle. To further determine the role of pulmonary mechanics in the pulmonary CO2-mediated BF response, Verapamil, a Ca++ blocking agent which blocks hypocapnic airway constriction, was administered to the vascularly isolated lungs of the dog. Verapamil blocked the hypocapnic airway constriction which occurred when pulmonary CO2 was reduced; however, the decrease in BF was not only blocked but in some animals there was an increase in BF. Also, the decrease in BF produced by hyperinflation of the lungs (Hering-Breuer reflex) was either blocked or an increase in BF occurred after administration of Verapamil.
mesh_terms: D000403:Airway Resistance / Q000187:drug effects; D000818:Animals; D002245:Carbon Dioxide; D004285:Dogs; D007545:Isoproterenol / Q000494:pharmacology; D008168:Lung / Q000098:blood supply / Q000502:physiology; D012018:Reflex / Q000187:drug effects; D012119:Respiration / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology*
chemical_list: D002245:Carbon Dioxide; D014700:Verapamil; D007545:Isoproterenol